From nobody Tue Apr 7 15:27:33 2026 Received: from sender4-op-o15.zoho.com (sender4-op-o15.zoho.com [136.143.188.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 78B68372B3D for ; Thu, 26 Feb 2026 02:57:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.15 ARC-Seal: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772074668; cv=pass; b=SIz4DxssaSbBkC1cFLuLQ6UKKQ71HcDJ4E0ex0SSYMfD5xZvrW5PWWxG7cjhLF2BlxRsKfA+EcQy9RKOEJkY8Di2coErw8cO0uNT2cvTWatCpXEHBVDfgcFJDYPhn6Lfh3YvQq7Y7PAKcRjXiBJ2BZ21naWwQTHYCvI7s2Pe0Ec= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772074668; c=relaxed/simple; bh=FTPzy2Ja9TzQHUhKRmFBDjXdPOtdEpZol0MHss4wVN0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=f2B4zqoffXXF4/U6N0ThKtI1AmXOLuldyF48IdSWa90IaqrTTiKqiwMJ/CDDalv1Hudv6HUCNl+1AUt6oi0/4ZRxJE2E88SY+XDx8KsOq64+k+EfaAJ01XgkZ58dntT7cCA49yCjGrbvLmpeYLPYeC1qpiiY+ixTO1XiFKZK5QA= ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.beauty; spf=pass smtp.mailfrom=linux.beauty; dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty header.b=erGro9/h; arc=pass smtp.client-ip=136.143.188.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.beauty Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.beauty Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty header.b="erGro9/h" ARC-Seal: i=1; a=rsa-sha256; t=1772074655; cv=none; d=zohomail.com; s=zohoarc; b=acwNJF8ZV+lMkKhv6RY6RWDeI2hEnkgylVAbLLRZnq/+GBkwwwm0rXKc0v7oayIvQSPnIrRxNPFNseH91TWcBFMCvDI7Q23X5hfX28qS/pAEmoDUC0KpAJMG9nDnuqqeeNU2OHqpBtkZ3LsBNkbAz3SiR5+btg62SlgmAEl9UoY= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1772074655; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=YYgP/LCldFwD04IaoaUAa6Vhao4j048xK5R4cG9FPOg=; b=aOtpJzpAVllEVjiG3jlUgYuzVo07blmeTEs0V+YJDfEawkGcnC+7kv4lIUVU++QhJvOpiLKFAxmJgmdYfHYGa9iw7bDto0f21lWTFx5M2gJhZNwoYFui2qX+jQOLGy/fyDHsDegMfOju1vBj6lJghjA8z6TsWGatWhoR2OvzD0A= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=linux.beauty; spf=pass smtp.mailfrom=me@linux.beauty; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1772074655; s=zmail; d=linux.beauty; i=me@linux.beauty; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=YYgP/LCldFwD04IaoaUAa6Vhao4j048xK5R4cG9FPOg=; b=erGro9/hNOh1zjykjUsw2nB9n1AwEZiUM0p6gqPSiRyA6yo2h4/r1YRDnFJRFqFn tQwFdhhw3o16wZYMobLfr+Mg88wTZuNQPFrAoPbIU4u/7fcXdKomBhjdxVV1Nzi9hq5 VYlFL4mrAj4zUW+OFGhnp6SxgUWO0nt8D4hl5Q+4= Received: by mx.zohomail.com with SMTPS id 1772074653879983.229166346284; Wed, 25 Feb 2026 18:57:33 -0800 (PST) From: Li Chen To: Pankaj Gupta , Dan Williams , Vishal Verma , Dave Jiang , Ira Weiny , virtualization@lists.linux.dev, nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Li Chen Subject: [PATCH v3 2/5] nvdimm: virtio_pmem: use READ_ONCE()/WRITE_ONCE() for wait flags Date: Thu, 26 Feb 2026 10:57:07 +0800 Message-ID: <20260226025712.2236279-3-me@linux.beauty> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260226025712.2236279-1-me@linux.beauty> References: <20260226025712.2236279-1-me@linux.beauty> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMailClient: External Content-Type: text/plain; charset="utf-8" Use READ_ONCE()/WRITE_ONCE() for the wait_event() flags (done and wq_buf_avail). They are observed by waiters without pmem_lock, so make the accesses explicit single loads/stores and avoid compiler reordering/caching across the wait/wake paths. Signed-off-by: Li Chen --- v2->v3: - Split out READ_ONCE()/WRITE_ONCE() updates from patch 1/5 (no functional change intended). drivers/nvdimm/nd_virtio.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c index a1ad8d67ad2d..ada0c679cf2e 100644 --- a/drivers/nvdimm/nd_virtio.c +++ b/drivers/nvdimm/nd_virtio.c @@ -18,9 +18,9 @@ static void virtio_pmem_wake_one_waiter(struct virtio_pme= m *vpmem) =20 req_buf =3D list_first_entry(&vpmem->req_list, struct virtio_pmem_request, list); - req_buf->wq_buf_avail =3D true; + list_del_init(&req_buf->list); + WRITE_ONCE(req_buf->wq_buf_avail, true); wake_up(&req_buf->wq_buf); - list_del(&req_buf->list); } =20 /* The interrupt handler */ @@ -34,7 +34,7 @@ void virtio_pmem_host_ack(struct virtqueue *vq) spin_lock_irqsave(&vpmem->pmem_lock, flags); while ((req_data =3D virtqueue_get_buf(vq, &len)) !=3D NULL) { virtio_pmem_wake_one_waiter(vpmem); - req_data->done =3D true; + WRITE_ONCE(req_data->done, true); wake_up(&req_data->host_acked); } spin_unlock_irqrestore(&vpmem->pmem_lock, flags); @@ -66,7 +66,7 @@ static int virtio_pmem_flush(struct nd_region *nd_region) if (!req_data) return -ENOMEM; =20 - req_data->done =3D false; + WRITE_ONCE(req_data->done, false); init_waitqueue_head(&req_data->host_acked); init_waitqueue_head(&req_data->wq_buf); INIT_LIST_HEAD(&req_data->list); @@ -87,12 +87,12 @@ static int virtio_pmem_flush(struct nd_region *nd_regio= n) GFP_ATOMIC)) =3D=3D -ENOSPC) { =20 dev_info(&vdev->dev, "failed to send command to virtio pmem device, no f= ree slots in the virtqueue\n"); - req_data->wq_buf_avail =3D false; + WRITE_ONCE(req_data->wq_buf_avail, false); list_add_tail(&req_data->list, &vpmem->req_list); spin_unlock_irqrestore(&vpmem->pmem_lock, flags); =20 /* A host response results in "host_ack" getting called */ - wait_event(req_data->wq_buf, req_data->wq_buf_avail); + wait_event(req_data->wq_buf, READ_ONCE(req_data->wq_buf_avail)); spin_lock_irqsave(&vpmem->pmem_lock, flags); } err1 =3D virtqueue_kick(vpmem->req_vq); @@ -106,7 +106,7 @@ static int virtio_pmem_flush(struct nd_region *nd_regio= n) err =3D -EIO; } else { /* A host response results in "host_ack" getting called */ - wait_event(req_data->host_acked, req_data->done); + wait_event(req_data->host_acked, READ_ONCE(req_data->done)); err =3D le32_to_cpu(req_data->resp.ret); } =20 --=20 2.52.0